The present invention relates to a system for conveying panels and shadow masks, for use in the process of manufacturing color picture tubes. More particularly, the invention is concerned with a system for conveying the panels and shadow masks independently between two adjacent processing apparatus such as shadow mask mounting or demounting apparatus and coating apparatus.
In general, the process of manufacturing color picture tubes includes a plurality of coating steps for forming, on the inner surface of the panel, a plurality of films such as a resist film, black matrix films, phosphor films and an emulsion film, and a plurality of exposing steps for exposing the coated panel after an insertion of the shadow mask into the latter.
For conducting these steps automatically, systems have been proposed, as in the specification of the U.S. Pat. No. 4,179,200, in which a plurality of coating apparatus and a plurality of exposing apparatus are arranged in a predetermined order along a panel conveyor line.
In designing and producing such systems, a difficulty arises as to the demounting and mounting of the shadow mask. Namely, it is necessary to demount the shadow mask from the panel for the coating purpose and then to mount the same shadow mask on the panel for the exposure. To cope with this demand, the system shown in the specification of the U.S. Pat. No. 4,179,200 incorporates a three-dimensional conveyor for conveying the shadow mask after the transfer of the panel from the conveyor line to the coating apparatus till the panel is transferred back to the conveyor line.
This system, however, has various problems. Namely, troubles are liable to be caused due to failure in obtaining a perfect synchronism between the operation of the coating apparatus through which the panel is passed and the three-dimensional conveyor by which the shadow mask is conveyed. In addition, for conveying the shadow masks by the three-dimensional conveyor, it is necessary to use specifically designed mask holders.
In order that the shadow mask, which has been temporarily demounted from the panel for the coating of the latter, is mounted again on the same panel without fail, it is considered to be the best solution to arrange such that not only the panels but also the shadow masks are conveyed through the coating stations.
From this point of view, it is suggested to use coating apparatus in which carrier heads carrying the panels and tables mounting the shadow masks are moved along predetermined paths. Such a system, however, cannot be realized successfully unless suitable system is developed for the convey of the panels and shadow masks between the mask demounting apparatus and the coating apparatus and between the coating apparatus and the mask mounting apparatus.